For the first time, fat-free chocolate milk processed with high-pressure jet technology has exhibited enhanced viscosity, stabilizing cocoa particles in the fluid. This significantly eliminates the need for added carrageenan, according to a team of Penn State researchers in the US.
They highlight that many consumers do not want the widely used seaweed-based food additive – which helps keep the liquid smooth and well-mixed even after days sitting on a store shelf – especially in organic chocolate milk.
Team leader Federico Harte, professor of food science, says the team initially did not expect casein proteins to have such a strong stabilizing effect on chocolate milk.
“We knew that breaking down the casein micelles – a kind of milk protein – would increase viscosity. However, the stabilizing effect could not be explained by the viscosity effect only.”
For example, when starch was added to chocolate milk to achieve the same viscosity seen with casein, no stabilizing effect was observed.
Because the new method offers industry a processing alternative to produce clean label, yet stable, low-fat chocolate milk, Penn State has applied for a provisional patent on the process and is working with a dairy food manufacturer to develop and scale-up.
An ingredient under scrutiny
Although the US Food and Drug Administration (FDA) has approved the use of carrageenan, concerns about its safety remain.
Harte says that some scientists believe that the additive can cause inflammation and digestive problems such as bloating and irritable bowel disease.
As a result, the additive is banned in infant formula in the EU.
“This research is not about being against carrageenan – it’s about consumers wanting clean food labels with only ingredients they recognize,” Harte comments.
“And carrageenan is not something they want in chocolate milk. We know that USDA has considered banning it for organic chocolate milk. Our results indicate that would be possible.”
“When carrageenan is removed from chocolate milk, a dense, difficult to disperse cocoa precipitate is formed,” Harte explains. “Gellan gum is used as an alternative to carrageenan. However, gellan gum and other potential stabilizers go against clean labels.”
Honing in on chocolate milk
In the study, researchers thermally treated fat-free chocolate milk formulations containing skim milk, cocoa powder and sugar, and then processed them using 125 to 500 megapascals high-pressure jet technology.
Carrageenan-free chocolate milk exhibited immediate phase separation of the cocoa powder, whereas formulations containing carrageenan were stable for 14 days, with cocoa particles not dropping out of suspension.
However, the researchers observed increased stability with increasing jet processing pressure, with maximum stability achieved when chocolate milk was processed at 500 megapascals.
“We believe that structural changes in casein micelles and new casein-cocoa interactions induced by high-pressure jet processing increased cocoa stability in the chocolate milk,” Harte outlines.
The stabilizing effect
In findings recently published in the Journal of Dairy Science, the researchers reported that formulations with 4%“micellar casein processed at 500 megapascals showed no phase separation over a 14-day storage period, stored at 39 degrees Fahrenheit.
When asked if there are any plans to look deeper into applications outside of chocolate milk, Harte says, the lab will continue to explore novel functionality from casein proteins in milk.
“The ultimate goal is to use milk and milk components as functional ingredients to remove unfamiliar stabilizers or emulsifiers,” he asserts.
Commenting on whether the results would be the same or similar for plant-based dairy alternative chocolate milk, Harte replies: “This is a maybe.”
“We believe the stabilizing effect comes from a specific group of proteins, i.e., the caseins. These proteins are not present in plant sources. Only research will tell whether stabilizing proteins can be found in plant sources,” he concludes.
